Jet lag and some sleep disorders are caused by a disruption in an individual's "internal clock." Understanding the most effective way to quickly re-adjust the body's internal clock will be beneficial for treating individuals with these conditions. This study will evaluate the combined effectiveness of light and non-light therapies at regulating sleep cycles and improving sleep quality.

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Primary Outcome Measures:

Circadian phase, as measured by the shift of the endogenous melatonin rhythm (measured during each inpatient visit) [ Time Frame: 24 hour ] [ Designated as safety issue: No ]

Secondary Outcome Measures:

Circadian phase, as measured by the shift of the endogenous temperature rhythm [ Time Frame: 24 hour ] [ Designated as safety issue: No ]

Sleep quality, as measured by wakefulness after sleep onset (electroencephalogram [EEG] defined wakefulness after 10 minutes of consecutive sleep) and number of awakenings [ Time Frame: overnight ] [ Designated as safety issue: No ]

Cognitive function, as measured by daytime sleepiness, reaction time, and mood and well being (all measured during each inpatient visit) [ Time Frame: 24 h and daytime ] [ Designated as safety issue: No ]

Circadian rhythm disorders are disruptions in an individual's circadian rhythm, or "internal body clock." This internal clock regulates the 24-hour cycle of biological processes in the body, including sleep and hormone production. Jet lag, delayed sleep phase syndrome, in which individuals fall asleep and wake up later than desired, and advanced sleep phase syndrome, in which individuals fall asleep and wake up earlier than desired, are all examples of circadian rhythm disorders. Because of the disruptive nature of these conditions, it is important to identify the quickest and most effective method for regulating the body and reestablishing normal sleep patterns. Light therapy, in which individuals are exposed to bright, artificial light, is currently used to treat these disorders. Melatonin, a hormone that regulates circadian rhythms, and methylxanthines, a class of stimulant medications, are other common non-light treatments. While each of these individual treatments has been proven effective, little is known about the combined effect of light and non-light treatments. The purpose of this study is to evaluate the safety and effectiveness of light therapy, melatonin, and methylxanthine, alone and in combination, at regulating circadian rhythms and improving sleep quality and cognitive function.

This study will enroll healthy individuals. Participants will first attend two screening visits, which will include a review of medical, psychiatric, and sleep histories; vital sign measurements; blood and urine collection; a physical examination; and an electrocardiogram. For 1 week, participants will record sleep habits in a diary and by telephone. They will also wear a device that monitors activity and light exposure levels. Eligible participants will then attend four 5-day inpatient visits at the Sleep and Chronobiology Laboratory at the University of Colorado at Boulder. During each of the four visits, participants will be randomly assigned to one of the following four treatments:

Dim light therapy and placebo

Bright light therapy and placebo

Dim light therapy, melatonin, and methylxanthines

Bright light therapy, melatonin, and methylxanthines

At each visit, participants will receive a different treatment. During these visits, participants will remain awake for up to 40 hours at a time, while their eye movements, and brain, muscle, heart, and breathing activity are monitored. Urine and saliva will be collected, and participants will undergo various cognitive performance testing measures. At 3-week intervals between each visit, participants will record sleep habits and will wear the activity and light exposure monitoring device. A sleep diary will also be maintained by participants for 3 weeks following the end of the last visit.

Eligibility

Ages Eligible for Study:

18 Years to 40 Years (Adult)

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

Yes

Criteria

Inclusion Criteria:

In good general health, as determined by blood chemistries, urine toxicology, physical examination, and medical and psychiatric history

Exclusion Criteria:

History of any current or chronic disease, including any of the following:

Chronobiologic disorders

Sleep disorders

Cardiovascular disorders

Respiratory disorders

Kidney and urinary tract disorders

Infectious diseases

Gastrointestinal disorders

Immune system disorders

Connective tissue and joint disorders

Hematopoietic disorders

Neoplastic diseases

Endocrine and metabolic diseases

Neurologic disorders

Current or past history of drug abuse

Pregnant or breastfeeding

Current oral contraceptive use

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00387179